X-ray tube



G. BUCKY April 9, 1929.

X-RAY TUBE Filed Aug. 20, 1926 INVENTOR GUSTAV BU CKY H BY mu ATI'ORIVEY Patented Apr. 9, 192 9 UNITED STATES PATENT OFFICE.

GUSTAV BUCKY, OF NEW YORK, N. Y.

X-RAY TUBE.

Application filed August 20, 1926, Serial No. 130,557, and in GermanyMay 8, 1923,

My invention relates to X-ray tubes and more particularly to such as areintended for the treatment of diseased or abnormal conditions of thehuman body. It is well knownv that X-rays have different degrees ofpenetration and that an X-ray tube may be caused to emit waves having ahigher or lower degree of penetration by adjusting the voltage impressedon the electrodes of such a tube. It is also well known that X- rays ofhigh penetrating power, so-called hard rays, have to be employed withgreat care on account of the danger of serious injury to internaltissues.

Whatever may be selected adjusted voltage, the emitted waves will alwaysbe so called hard rays as the walls of the tube, as generallyconstructed, absorbs the soft rays and especially the very soft rays.Even where it has been attempted by the use of a gas-filled X-ray tubeprovided with a glass window, the elements of which have low atomicweights, to afford an opportunity for the soft rays to pass through thewalls of the tube, hard rays also pass through, and soft rays of lowintensity were never maintained or capableof being maintained. I havefound, however, that if treatments are applied with very soft rays ofmaintained low intensities, effects of an unusual and hitherto unknowncharacter can be produced. With X-ray tubes as conwith which I amparticularly concerned in this case. In order to permit the soft rays topass out of the tube as rays of maintained lo'v intensities, I employ awindow of a character which offers much less resistance to soft X raysthan ordinary glass and is substantially pervious to such rays. Theresistance which a substance olfers to the passage of X-rays depends onthe thiclmess of the substance and somewhat, apparently, on the atomicweights of the chemical elements of which such substance is formed.Ordinary glass consists chiefly of sodium or potassium, calcium, andsilicon, the atomic weights of these four elements being 23, 39, 40, and29, respectively. When an X-ray tube is constituted of the said ordinaryglass of the usual thickness, substantially all of the soft rays areprevented from emerging from such a tube. In my improved X-ray tube, Itherefore preferably employ a window made of a substance, theconstituents of which have a much lower atomic weight than those ofordinary glass, although 1 may, in some cases, employ a window made ofvery thin ordinary glass, say 0.1 mm. in thickness or made of berylliumor of aluminum. As an instance of a preferred type of window, I employ awindow of the so-called Lindemann glass which is made of elements noneof which has anatomic. weight higher than 16. It will be obvious thatwith such windows X-rays of much lower penetrating power can passthrough to the outside of the tube, and become available for curativepurposes, than when the entire bulb consists of ordinary glass of theusual thickness. It is iniportant, however, in View of my requirement ofa maintenance of soft rays of low intensities, that the X-ray tubeshould be of a character which permits the maintenance of sustained 10wtensions and enables the penetrating power of the rays to be adjusted topredetermined voltages within said low tension range. I make use of atube of the so-called heated cathode type, as illustrated for example bythe Coolidge patents, for instance, No. 1,203,495. l/Vhen I refer to atube of the heated cathode type, I mean a tube which permits thepenetrating power of the X-rays maintained as soft rays of lowintensities to be varied by altering the voltage of the dischargepassing through the tube, but keeps such penetrating power constant aslong as said voltage remains unchanged.

In the use of an X-ray tube emitting soft rays, it is desirable foreffective and uniform treatment of a patient that the field covered bythe soft rays be as great or greater than the whole of the area to betreated. With X-ray tubes having a Lindemann glass window incorported ina tubular extension of the glass bulb, only a limited field can beobtained, thus necessitating scanning of the entire area under.treatment, i. e. shifting the field from one position to another untilall of the afilicted portion of the patient has been exposed to X-raytreatment. This, of course, does not give a uniform treatment as oneportion is likely to be over-treated and another portion under-treated,nor is it generally a wholly satisfactory practical procedure. In myimproved X-ray tube I preferably incorporate the soft ray transmittingwindow in such a position with respect to the anti-cathode that thesolid angle of the cone of rays is relatively large and the fieldcovered by the rays is correspondingly large. By the use of a tube ofthis character I am able to treat, under the more general conditions, anafllicted portion of a patient with one exposure and without thenecessity of scanning the area under treatment. It will be apparent,therefore, that more effective and uniform and better controlledtreatmentsmay be given with my improved X- ray tube than hitherto waspossible with tubes having very limited soft ray emitting areas. Theusual hot cathode type of X-ray tube is constructed so as to respond toa wide range of voltages. Inasmuch, however, as the more importanttreatments with my new tube are generally within the range ofapproximately 5 to 15 kilovolts, I prefer to construct my tube as iswell understood by those skilled in this art, so that it will have alimited voltage capacity, the upper limit being generally about 15kilovolts. The result, of course, is that with such a tube any danger ofoperating, even accidentally orinadvertently with rays of higherintensities than those desired is excluded. Thus my tubes ma be usedwith great safety and without ear of harmful action on the patient.Speaking generally, some of the more important treatments are appliedwith X-rays of approximately 1.8 Angstrom, having a half valueabsorption in aluminum of approximately 0.0323 mm.

By a combination of the aforementioned features I obtain results whichhave not been available hitherto and which thus far have not even beenunderstood or appreciated.

The present invention will be readily understood from the followingdescription taken in conjunction with the embodiments of my inventionillustrated in the accompanying drawings, in which Fig. 1 shows anelevational view, partially in section for purposes of clarity of apreferred embodiment of my invention and Figs. 2 and 3 are views similarto Fig. 1 of modified forms of my invention.

Referring now more particularly to Fig. 1, the numeral 1 designates abulb, preferably cylindrical in cross-section, made of ordinary glassand having a tubular exten-. sion 2 projecting from the side thereof. Inthis extension wires 3 and 4 are sealed and are electrically connectedto cathode 5 positioned within the tube. This cathode has a heatingarrangement, for instance, such as the one employed by Coolidge,enabling the degree. of hardness of the rays to be varied ina'well-known manner. Sealed in one end of bulb 1 is an anti-cathode 6which may be made, for instance, of aluminum or magnesium. It has beenascertained that these metals, which have a low atomic Weight, are ofespecial advantage in the production of soft X-rays. Not only do tubeswith anticathodes of such metals produce a very high proportion of softrays (accompanied by a relatively small proportion of harder rays) butthe potential employed'may be much lower than with anti-cathodes of highatomic weight, and'the potential may be inci eased up to about twice theinitial or starting potential Without altering the characteristic thatthe discharge consists predominantly of soft rays. The anti-cathode hasa cooling jacket 7 associated therewith in a manner well known to thoseskilled in the art. This jacket has an inlet tube 8, through which thecooling water is introduced and an outlet tube 9 through which thecooling water is withdrawn from the jacket. This holder has ananti-cathode 6 with aface 10 secured to the inner end thereof so as toreflect the rays emitted by the cathode to a window 11. This window asin the case of Fig. 1 may be made of very thin o'rdinary glass (0.1 mm.thick) or of Lindemann glass pervious to substantially all of the softrays and may be secured to bulb 11 in any well-known way. The soft rayemitting area provided by window 11 is materially larger than any of theconven tional Lindemann windows incorporated in ordinary X-ray' tubes,so that improved results may be obtained by the use of my new X-raytube.

Another modified embodiment of my invention designed especially formonth and throat treatment and the like is shown in Fig. 3, wherein thenumeral 1 designates a bulb of very small dimensions and preferablycylindrical in cross-section. At one end of the bulb electricallyconductive wires 3 and 4 leading to an axial cathode 5 are sealed.Adjacent the cathode 5 and protruding from the side wall of bulb 1 is ananti-cathode 6 with associated cooling jacket 7. An inlet tube 8 leadsthe cooling water to the jacket 7, whereas tube 9 conducts the wateraway from the jacket. The face 10 of the anti-cathode, as usual, is setat an angle so as to reflect the rays emitted from the cathode throughwindow 11; This window, as noted heretofore, is made either of very thinglass (0.1 mm. thick) or preferably of Lindemann glass substantiallypervious to the softer X-rays and is positioned as close to theanti-cathode as is permissible, so as to include as large a solid angleA as is possible or desirable. In order to prevent any possibility ofthe patient receiving a shock, the anti-cathode is grounded by means ofa wire 12 running to a ground 13. The

whole tube shown in Fig. 3 is so small that it can be used in a patientsmouth or throat without the least difficulty. Of course, as usual withinstruments of this character, well-known observation and control means(not shown) are provided with my improved X-ray tube for watching anyportion under treatment and directing the rays emitted by my tube tosuch portion.

Tubes of the character heretofore set forth are very etiicient toproduce X-rays of very great softness, in fact X-rays having apenetrating power considerably below any available hitherto, and arecapable of emitting a cone of soft rays having a large solid angle andthus covering a relatively large field. In other words, my improved tubeenables X-rays to be produced and to be sent outside of the tube whichhave a wave length greater than any X-rays produced hitherto, it beingwell-known that the greater the wave length, the smaller the penetratingpower. Owing to the employment of the heated cathode type of tube, 1 amenabled to vary the penetrating power of these soft X-rays. The effectof these extra-soft X-rays is very remarkable and in many cases isapparently physiological rather than morphologically destroying or'paralyzing, and a very important feature. of their use is that harmfulresults are not likely to occur even when the exposure is very long. Iam enabled, for instance, to produce X-rays which will affect only theoutermost horny layer of the skin or only the automatic nerve system ofthe skin without striking deeper layers of the body and these areresults which have never been obtained hitherto with -X-rays. In otherinstances, for example, in the treatment of eczema, it was found thatitching was stopped within two hours after a treatment, and the eczemaitself disappeared within twenty-four hours, results which can beproduced with ordinary X-rays only after several days. Acne andpsoriasis have disappeared within relatively short periods afterapplication of the new X-rays. Exposure to X-rays such as produced by myimproved tube has produced a diminution of the leucocytes lasting for ashort time, the effect being similar to that observed when the Muellerintracutaneous injection is employed. This diminution of the number ofleuccocytes is characteristic of reactions taking place only within theskin but not below it, and, therefore the strong diminution of thenumber of leucocytes for a short time is an indication that the raysfrom my new tube produce a strong intracutaneous reaction.

It will be obvious that the principles underlying my new tube can beincorporated in tubes of widely differing sizes, shapes or arrangement,according to some special use or requirement. Modifications of thatcharacter, so long as the fundamental features of this invention areretained, are intended to be included within the scope of the claims.

This application is in part acontinuation of my application, Serial No.711,561, filed on May 7, 1924, now Patent No. 1,679,332, issued July 31,1928.

I claim:

1. An X-ray tube of theheated cathode type adapted for emitting softX-rays of adjustable penetration provided with a cathode, ananti-cathode and an X-ra transmitting portion pervious to the so .tX-rays and so positioned with respect to the anti-cathode that the coneof rays emitted from the latter has a relatively large solid angle.

2. An X-ray tube of the heated cathode type adapted for emitting softX-rays of adjustable penetration, said tube being provided with an X-raytransmitting portion pervious to the soft X-rays and of relatively largesoft X-ray transmitting area.

3. An X-ray tube of the heated cathode type adapted for emitting softX-rays of adjustable penetration, provided with a cathode, ananti-cathode, and an X-ray transmitting portion made of a substance, theelements of which have a relatively low atomic weight, said X-raytransmitting portion being arranged with respect to the anti-cathode sothat a cone of soft rays with a large solid angle is emitted from thetube.

4. An X-ray tube of the heated cathode type adapted for emitting softX-rays of adjustable penetration, said tube including a cathode and ananti-cathode adapted for operation at sustained low tensions and beingprovided with an X-ray transmitting portion pervious to soft X-rays andpositioned with respect to the anti-cathode so that the cone of raysemitted from the latter has a large solid angle.

5. An X-ray tube of the heated cathode type having an anti-cathodecapable of emitting soft X rays and a glass bulb pro vided with an X-raytransmitting portion adapted for transmitting soft X-rays of adjustablepenetration, said X-ray transmitting portion being made of a glass, theelements of which have a much lower atomic weight than those of saidbulb, and having a relatively large soft X-ray transmitting area.

6. An X-ray tube of the heated cathode type having a glass bulb ofsubstantially cylindrical cross-section, a cathode projecting from theside of said bulb, an anticathode capable of emitting soft X-raysoperatively associated with said cathode secured in one end of saidcylindrical bulb, and an X-ray transmitting :portion made of a substancenon-absorptive of soft X-rays and so positioned with respect to saidanticathode that the cone of rays emitted from the latter hasarelatively large solid angle.

7. An X-ray tube of the heated cathode type having a glass bulb ofsubstan tially cylindrical cross-section, a cathode within said bulb, ananti-cathode capable of emitting soft X-rays operatively associated withsaid cathode, and an X-ray transmitti n portion of materialnon-absorptive of sott rays forming substantially the Whole of theclosure at the lower end of said bulb.

8. An X-ray tube of the heated cathode type adapted for emitting softX-rays and for functioning close to the body of the person undergoingX-ray treatment, said tube having an X-ray transniitting portion ofmaterial non-absorptive of soft X-rays and of relatively largetransmission area,

said X-ray transmitting portion being located relatively close to theanti-cathode so as to provide for the transmission of a. cone of rayshaving a relatively large solid angle and passageways for cooling meansassociated with said anti-cathode to positively remove heat from thelatter and thereby to protect the patient from injurious heat effects.

9. An X-ray tube of the heated cathode type having a glass cylindricalbulb of such limited size as to fit in a persons throat, a cathodepositioned substantally axially with respect to and adjacent to one endof said cylindrical bulb, an anti-cathode capable of emitting softX-rays adjacent to said cathode, and a window opposite to saidanticathode and forming a part of the side wall of the bulb at thecathode end of the cylinder, said window being made of a substancenon-absorptive of soft X-rays and positioned with respect to saidanti-cathode so that the cone of rays reflected from the latter has arelatively large solid angle.

10. An X-ray tube of the heated cathode type having a glass cylindricalbulb of such limited size as to lit in a persons throat, a cathodepositioned substantially axially with respect to and adjacent to one endof said cylindri(.- al bulb, 'an anti-cathode capable of emitting softX-rays adjacent to said cathode, grounding means associated with saidanti-cathode, and an X-ray transmitting portion opposite to saidanti-cathode and forming a part of the side wall of the bulb at thecathode end of the cylinder, said X-ray transmitting portion being madeof a substance non-obsorptive of soft X-rays and positioned with respectto said anticathode so that the cone of rays reflected from the latterhas a relatively large solid angle.

In testimony whereof I have hereunto set my hand.

GUSTAV BUCKY.

